This program is designed to provide a multidisciplined approach to the study of the physiological significance of in vitro blood rheology studies. The experimental approach to the problem involves: 1) the development and accumulation of techniques necessary to acquire various hemorrheological data (such as low or high shear rate viscometry, cellular deformability, erythrocyte morphology-shear stress relations) on physicochemically and morphologically defined blood samples; 2) the continued development of a relevant in vitro flow replica, derived from a vascular bed, suitable for viscometry as well as flow visualization; 3) the systematic use of these instruments and techniques to define more fundamental properties of human blood, with particular emphasis directed toward detailing physical-rheological changes in stored blood. Additionally, it is proposed to utilize these techniques to provide hemorrheological data as potential supporting information for patient care.